For a wireless communication device, such as a broadband wireless communication device, calibration can be performed to assure that accurate radio frequency (RF) power is transmitted at an antenna connector of the wireless communication device. The calibration can be sensitive to the effects of impedance of the antenna connector. Such impedance can be referred to, or attributable to, voltage standing wave ratio (VSWR) effects.
A specific RF power is to be provided at the antenna connector, and particularly a specific RF power to be transmitted by an antenna of the wireless device. For transmitted power, a goal is make the transmitted power accurate, but there may be constraints to work around. The constraints can include regulatory standards as to operational minimum and maximum values of transmitted power, and consideration as to signal integrality, including signal linearity.
Change in VSWR can cause a significant error in transmitted power, leading to calibration errors; for example calibration errors of +/−2 dB. The effect of such calibration errors, can lead to having to provide for stronger and costlier power amplifiers, and in certain cases, to back off power to prevent regulatory violations regarding transmission. In such cases, significant costs and design issues can arise. It would be ideal to use less powerful power amplifiers to save power consumption, and avoid introducing additional components in order to reduce size of wireless communication devices.
The wireless communication device transmits desired signals and information at the antenna; however, VSWR changes can occur, and in RF terms, the antenna should be matched to a power amplifier providing the signals. If no matching is provided, problems can occur affecting the signals and information.
With typical calibration techniques, a significant window of error can exist, because of the unknown matching of the antenna and lines or coupling to the antenna. From the power amplifier, there can be considered an interface to the antenna. The interface can be defined by the lines, including a coupler that connects the power amplifier to the antenna. In certain cases, the coupler can be a detector that detects signals that are transmitted through the lines. The coupler can also be a sampler that samples actual power that is transmitted.
In certain cases, there can be a discrepancy as to the reading at the power amplifier and the reading of the power that is transmitted at the antenna. Existing detection methods can have considerable error (e.g., +/−2 dB), and the window of error between desired power transmission and actual transmission can be large. This can lead to problems in not having sufficient power to meet regulated power transmission, or having too much power as to regulated power transmission requirement. Either way, this leads to issues of power consumption and power size. In general, power performance issues are of concern. Therefore, there is need to improve power detection and calibration in wireless devices.